With digital communications in a multipath environment and orthogonal frequency division multiplexing (OFDM) encoding techniques, an array-of-subarrays (AoSs) architecture has been adopted in transmitters and receivers. For example, multiple antennas are included in a sub-array and each transmitter/receiver includes an array of such sub-arrays. Such AoSs architecture may be used, in multiple-input multiple-output (MIMO) communication systems as well as millimeter-wave broadband (MMB) communication systems.